The goal of this project is to elucidate the factors that modulate cardiac arrhythmias by working on the following three areas: (1) simulating the effect of antiarrhythmic drugs on cardiac arrhythmias by means of computer modelling, (2) developing "accurate" algorithms which will allow us to extract the kinetic parameters from the single channel patch-clamp recordings, and (3) characterizing new types of chaos that may arise from cellular excitability. To achieve the first goal, we will study the effect of agonists and antagonists of Na+, Ca2+, and K+ channels by means of computer modelling and bifurcation analyses. This study will allow us to find the factors that cause the proarrhythmic effect by antiarrythmic drugs and suggest means to treat cardiac arrhythmicas effectively using these drugs. In the second approach, we will develop an "accurate" algorithm by combining entropic maximization with the maximum-likelihood analysis method. Using this algorithm, we will el ucidate the quantitative role of the Ca2+ channels in the ventricular cells. To achieve the third objective, we will carry out a bifurcation analysis on the excitable cell models developed by our group. This study will lead us the characterization of new types of chaos that are associated with cardiac cells and neurons.